User

• Add a user

$ sudo adduser <username>

• Add a user to groups

$ sudo usermod -a -G group1,group2 user

• Add a user to sudoer in Debian

$ su -
# usermod -a -G sudo <username>

sudo -l -U <username> # check if the user has sudo

Misc

• Change the hostname

sudo hostname new-server-name-here
# Also edit /etc/hostname and /etc/hosts
# OR hostnamectl set-hostname new-server-name-here